/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.nutch.net.protocols;

import java.util.Calendar;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;
import java.text.SimpleDateFormat;
import java.text.ParseException;

/**
 * class to handle HTTP dates.
 * 
 * Modified from FastHttpDateFormat.java in jakarta-tomcat.
 * 
 * @author John Xing
 */
public class HttpDateFormat {

	protected static SimpleDateFormat format = new SimpleDateFormat(
			"EEE, dd MMM yyyy HH:mm:ss zzz", Locale.US);

	/**
	 * HTTP date uses TimeZone GMT
	 */
	static {
		format.setTimeZone(TimeZone.getTimeZone("GMT"));
	}

	// HttpDate (long t) {
	// }

	// HttpDate (String s) {
	// }

	// /**
	// * Get the current date in HTTP format.
	// */
	// public static String getCurrentDate() {
	//
	// long now = System.currentTimeMillis();
	// if ((now - currentDateGenerated) > 1000) {
	// synchronized (format) {
	// if ((now - currentDateGenerated) > 1000) {
	// currentDateGenerated = now;
	// currentDate = format.format(new Date(now));
	// }
	// }
	// }
	// return currentDate;
	//
	// }

	/**
	 * Get the HTTP format of the specified date.
	 */
	public static String toString(Date date) {
		String string;
		synchronized (format) {
			string = format.format(date);
		}
		return string;
	}

	public static String toString(Calendar cal) {
		String string;
		synchronized (format) {
			string = format.format(cal.getTime());
		}
		return string;
	}

	public static String toString(long time) {
		String string;
		synchronized (format) {
			string = format.format(new Date(time));
		}
		return string;
	}

	public static Date toDate(String dateString) throws ParseException {
		Date date;
		synchronized (format) {
			date = format.parse(dateString);
		}
		return date;
	}

	public static long toLong(String dateString) throws ParseException {
		long time;
		synchronized (format) {
			time = format.parse(dateString).getTime();
		}
		return time;
	}

	public static void main(String[] args) throws Exception {
		Date now = new Date(System.currentTimeMillis());

		String string = HttpDateFormat.toString(now);

		long time = HttpDateFormat.toLong(string);

		System.out.println(string);
		System.out.println(HttpDateFormat.toString(time));
	}

}
